Less Water Being Held in Most US Snowpacks

Most U.S. snowpacks are now holding less water, scientists have found.

Snowpack, and the amount of water it stores, is crucial to water management practices around the world, as it's vital for drinking and irrigation and provides protection against drought. Now, a new technique developed by Oregon State University's (OSU) College of Engineering has provided more information about the water a snowpack stores.

Based on nearly 40 years of snowpack data, the study was published in Hydrology and Earth System Sciences and led by OSU professor David Hill and doctoral student Christina Aragon. The researchers found a 22 percent drop in how much water is stored in snowpacks every year in the Lower 48 states.

These findings are important because they provide not just a better tool for estimating the amount of water stored. They also tell researchers more about mountain snowpacks in general and how they are changing.

The study found that 72 percent of all water stored through snow lies in the mountains in the Lower 48 states, even though mountains cover just 16 percent of the entire area.

"Over the long term, changing climate dominates snowpack changes. In some areas, a portion of this can be attributed to changes in precipitation amounts," Hill told Newsweek.

"But, overwhelmingly, on the climate side of things snowpack changes are due to warming temperatures," he continued. "Here in the Pacific Northwest, for example, most of the state of Oregon in this past December ran about 5 degrees F above average. So many areas see precipitation amounts that have not changed all that much, but more of the precipitation is now falling as rain and not snow.

The new model should help water managers estimate snowpack storage in the future "amidst a future of increased climate variability," Hill said.

Other factors can reduce snowpack, he said, and many of these could be described as "landscape" changes.

"I will give you two examples. Some areas are increasingly seeing 'dust on snow' events. The Wasatch Range in Utah is a good example. Dust blows in from the west and deposits on the surface of the snow," Hill said. "This darker material absorbs more sun and accelerates the melt of the snow. Second, consider forest fires which leave behind a radically altered landscape. There are many studies that look at how snowpack behaves in burnt landscapes.

"So the primary driver of changing snowpack is warming temperatures," Hill said. "But there are secondary effects as well. Of course, these landscape changes are, themselves, commonly associated with climate change, [such as] more forest fires in the West. Great Salt Lake in Utah drying out."

Climate change is causing more extreme weather patterns across the U.S., particularly in the West, which until recently faced a water crisis due to prolonged drought conditions.

"From local to regional scales," Hill said, all water users need to balance the demand with the supply. This is why knowing more about snow storage can be vital.

"As we move forward, and as we have moved from the past to the present) the relatively good news is that annual precipitation amounts tend to not change that dramatically in many areas," he said.

"However, changing temperatures greatly influence snow storage and therefore the timing of water availability," he went on. "Water managers tend to consider a portfolio of infrastructure options to match supply to demand, and increased understanding of snow water storage should allow them to make long-term planning decisions for how to adjust that portfolio."

Other avenues will be explored in this area of research, including the "distribution of snow and precipitation events," Hill said.

Update 3/18/23,1:47 p.m. ET: This story was updated to include comments from Oregon State University's David Hill.

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